Obsession
by ItalianFlower
Summary: We all have Obsessions. Including Derek. Only his fantasies are darker than most...
1. Part 1

Note: This is supposed to be creepy. Very, very creepy, in fact. If you are sufficiently creeped out, then that is the appropriate response. Sorry. Here, the characters are slightly out of character, but I believe that they are not too off, because I tried to simply shift some basic values a little and this is what I got. Also, I think anyone and everyone is capable of any and every evil, whether they actually do it or not. So there is my justification. However, this is very AU, just to warn you if you don't like AU very much. Also, the rating I have is more for themes than content, because _most_ of it is implied, rather than explicit (and I think it is more powerful that way). But if you could let me know if I am justified in putting it so high, that would be grateful. And if you actually read this whole thing, bravo!

Disclaimer: This applies for the whole story. I don't own _Life with Derek_. I promise you, if I ever do, you will be the first ones to know. Also, if I did, it would be very different. And probably not Disney-Channel-showable.

* * *

He had been attracted to her since the day they had met.

This was not all that surprising, though, despite their situation. After all, teenage boy plus good-looking girl equals instantaneous attraction, lust, and infatuation.

Herein lied his problem. For he should not be attracted to this girl; it defied all moral and ethical codes of conduct. And even though he usually cared not for these things, there were some lines he would not allow himself to cross. You know, the ones about not killing other people, abusing women, robbing casinos, becoming Obsessed with your stepsister…The obvious ones, of course.

Well, not crossing three out of those four is not so bad, is it?

Yes, this was his problem—he was infatuated with and slowly becoming Obsessed with her, his stepsister.

It started with the evident attraction.

Perhaps, if she had been any other girl (_any other woman's daughter_), he would have taken her out on a date (_maybe a few?_) and then she would have been out of his system like all his other exes. But, due to the forbidden nature of a romantic relationship between the two, that could not happen. And because she was forbidden, out of reach, she became so much more desirable. Humans always want the most what they cannot have.

Perhaps, if she was meek, docile, and everything he _said_ he wished she was (_boring_), she would not have been so attractive. But her fighting spirit and fiery temper during their rows had a way of igniting a fire within him he did not know how to put out (nor did he want to, if he was being honest). And they fought oh so often!

After the attraction came the lingering thoughts.

It started with strange dreams he could not always remember (nor care to), with hints of desire. Then they came with greater frequency, and with much more clarity. During his waking hours, he found these thoughts and desires to be disturbing; during the night, on the other hand, he found himself looking forward to his dreams and encouraging them with excessive—and sometimes filthy, I regret to say—thoughts.

And lastly, came the all-consuming Obsession.

Now the thoughts of her encompassed him both day and night. The thoughts during the day remained the "innocent" fantasies typical to a teenage boy—though they were really only innocent in light of his nighttime cravings. The night was reserved for his darker, more carnal fantasies, the ones that were sick, bloody, terrifying, and oh so desirable. During they day, his fantasies so revolted him, he wished to vomit to rid himself of the feeling. But at night, desire would onset and he would seem a different person, with those disgusting thoughts floating through his head. Those thoughts that no person should think of another, than no man should think of a woman, that no gentleman should think of a lady.

The thoughts no brother should think of a sister, stepsiblings though they were.

There is a funny thing about desire and temptation. It always seems better, more enticing in the dark. And it was then that he desired his sick, twisted fantasies solely for their sick, twisted nature. The despicable had become the object of the desire because it was gross and revolting, not because it was necessarily desirable. But after those moments passed, he always felt so _dirty_, but during those moments, he was giddy with pleasure. (It seemed so _real_. And it was so _wrong_. But it felt _so_ good!)

Dark Obsessions rarely ever end well.

* * *

He could feel himself becoming desperate. He needed to do _something_ to release his pent-up feelings. Thinking and visualizing these things were no longer enough; his mind had become tolerant to the sick pleasure of it and demanded _more, more!_ Plus, his gross fantasies were no longer chained to the dark, but were unleashed and haunted his waking, daylight hours, as well. He felt a growing need to dominate and control his feelings.

He felt a growing, primal need to dominate, posses, and control _her_.

They were beginning to notice, so he had to do something soon, or he might never rid himself of this Obsession in his head. The family was going on a weekend vacation, and the two eldest would be left alone in the house. It was perfect for his plans. The thought of the house being empty except of him and _her_ made him shiver with pleasure.

He only hoped that his Obsession was not too obvious that anything that might happen could be linked back to him. And he _sincerely _hoped she would not be _too_ hurt by the end of the weekend.

But it was no matter, even if it was forbidden and wrong. 'Cause Derek always got what Derek wanted.

_Of course?_

Of course.


	2. Part 2

From the moment they had met, she knew he would mean lots of trouble for her. His cocky attitude, his disrespect for everyone, and his selfish, self-absorbed manner were just the tip of the iceberg. All this she had picked up in the first moments of meeting him. Of course, it was not as if he tried to hide it.

However, though, after spending a few years with him and getting to know him better, she learned that he was really a good guy at heart. The love with which he treated his sister was more than enough evidence of that. And he _had_ actually stood up for her a couple times! Crazy, of course, but welcome nonetheless.

It was funny how her feelings about him and their fights had evolved over the past couple years.

At first, she absolutely hated their fights. He would _always_ win and make her feel so demeaned and small. He never showed any respect, and always went out of his way solely to make her feel bad. It was an awful first year for her, and probably not at all horrid for _him_. After all, he was a _bad guy_; he liked to humiliate others.

In the next year, their spats were much the same, but she looked forward to them a little bit. She would learn that his behavior would often challenge her to grow, even though he had not set out to do so. It was also a great way to release stress and bad feelings (never mind that he was also the cause of those as well). And, to be honest, she probably enjoyed humiliating him, too. (_He is rubbing off on me!_)

As they grew a bit closer, she noticed that they actually began to get along occasionally, _occasionally_ being the key word, that is. And it was then she began to notice the good person he was beneath his façade. However, if she told herself the truth, she missed fighting with him a lot, and made up for it by throwing her everything into the fights they did have and into annoying him (to provoke a fight, of course). It almost seemed as though she had an Obsession with this petty fighting, and could not let it go to mature. (_What is wrong with me?_)

However, lately she had been getting her wish and they had been fighting more often, leaving her giddy to be so mad at him and _feel so much_. But something strange often occurred at the end of a spat. He would always give her an off look that seemed to be a combination of the look a guy attracted to her might give her, with a little _What the heck?!_ thrown in, and a little of that Obsessed, crazy look that the serial killers had on television to top it all off. After a second or do, he would always shake in his head (_With what? Disgust, shame, self-loathing? Utter confusion?_), and leave the room.

It always left her with ambivalent feelings.

Sometimes, that look would simply confuse her, and she would simply return the _What the heck?!_ component of the gaze (_dumb, immature boys_).

Other times, she would tingle with pleasure, her body responding to the gaze of a good-looking guy checking her out (for that is what part of his look was, whether she recognized it or not. And he was physically attractive, she had to admit). She would always shiver a little, before turning away and blushing. Then she would go to her room and promptly forget about it.

The other response she had was a cold, dreaded fear that formed a knot in her stomach, which would cause her to slowly back away from that awful smirk. She would turn and run away to somewhere with many people about, her heart pounding so loud she was afraid all could hear it, including him.

Most of the time, it was a combination of the three mixed together, probably the byproduct of an overly Obsessed mind.

Crazy Obsessions rarely ever end well.

* * *

Recently, she had been having strange dreams about him. At first, she could not remember them, just the fear that lingered when she woke with a start. Then later, she could remember, and she wished she had not. For her dreams were recurring nightmares in which he did horrible, sick, and twisted things to her, leaving her incapacitated and leaving him with power, dominance, and pleasure. She now always woke with a shudder that tried to shake away all the cobwebs from her nightmares.

They were only nightmares, right? Of course.

However, she was hesitant to write them into her dream journal, for if he found out, he would never stop tormenting her for it. And that was one fight in which she genuinely did not want to involve herself. But the funny thing was, he always had that same look on his face. The same look which so confounded her.

So when their parents said they were taking the weekend for a vacation, leaving the two oldest at home alone, she almost asked her mother not to go. She had been seeing the frightening aspect of his gaze for the past month, and that, with her nightmares, left her anxious to be alone for the weekend with him.

However, she brushed her fears aside as irrational. After all, a dream was only a dream, and was not actually _real_.

And besides, Derek was a good guy at heart, and would never do anything to seriously harm Casey.

_Of course._

Of course?


	3. Part 3

As a warning, the second half of this chapter is much darker than the previous ones have been.

* * *

Obsession is a strange thing.

It makes people do odd things, things one would never expect him or her to do. It causes irrational, crazy behavior. It destroys inhibitions, ruins lives, impairs relationships. Yet, we so often let ourselves be overcome by Obsessions, and cling desperately to them like a safety blanket.

If we are honest with ourselves, we will be shocked to find that we willingly cast aside our genuine relationships so easily to wallow in the dark with our unhealthy Obsessions, for they make us feel good—for a time—no matter how wrong it is.

If we honest with ourselves, we will also reluctantly admit that we _all_ have our own personal Obsessions. Perhaps it is not the dark desires of a serial killer, nor is it the strange longings for a forbidden and slightly unhealthy relationship. Rather, it might be that one television show we just _have to see_ every week. Or maybe it is finding _all about_ miss-famous-so-and-so, and being up to date on all the gossip. Perchance it is the meeting of lovers, whether they are in an illicit relationship or not.

Is it not strange that we _all_ have Obsessions, both large and small?

I think there must be a reason for having Obsessions, and that there is a healthy outlet for it. Maybe we were all designed to long and desire for Something or Someone. Maybe there is a Magnificent Obsession just waiting for us to find it and be complete, whole. Maybe there is an Obsession that causes us to do the right thing, compels us to become better people, and drives us to help other people find the best thing we have in our lives.

Maybe there is Someone who created us and designed us to Obsess over Him. One who designed us to not be complete without Him.

But maybe there is Someone Else who twists this desire, to make us forever incomplete, forever unhappy, forever unfulfilled. Someone Else who wishes us to be eternally hurt and twisted and desires us to eternally hurt and twist others. Someone Else who wishes to destroy and kill our Souls during it all.

Bent Obsessions never end well. They are deadly. They cause us to lose our souls.

* * *

The weekend was over, and the parents walked into the house.

The mess waiting there for them astounded them.

_They threw a party? Again?!_ were the simultaneous thoughts of both husband and wife. At first glance, the living room seemed to have been trashed by a bunch of rowdy teenagers. There were broken furniture, overturned bookshelves, a hole in the wall, and random food littered the ground. (Though the food was not necessarily from a party. The eldest was a bit of a slob.)

They all continued on with this assumption, too shocked to yell—yet—for their oldest children. That is, until the youngest one asked a question.

"Daddy? Why do Smerek and Casey get to finger-paint on the walls, and I don't?" She queried, pointing to a red handprint on the wall going to the upper level of their home.

"What do you mean? Derek and Casey aren't allow…" he trailed off as his gaze followed the little girl's finger to where she was pointing. He blanched at the sight of the bloody handprint on his wall. His mind started spinning, _Are the kids all right? Was there an intruder? Are we too late? What happened?_ The wife had noticed at the same time as her husband the blood stained on the walls. Upon closer inspection, the hole in the wall had a red tinge around it, and lots of the furniture had bloodstains on it, too.

"Kids, stay here," came the adults' firm command as they raced up the stairs to find their oldest children, calling their names and trying to ignore that hole in the stomach that was steadily growing bigger and bigger. They first checked in their respective rooms, which seemed to be as trashed as the living room. The beds were especially damaged.

That is when they stumbled into the bathroom, where they found the body of one of their children—mutilated almost beyond recognition, covered in sweat, tears, and blood, and very dead. It was much too clear what had happened here.

A closer search of the house revealed that the other teen was missing.

The terrified screams from the McDonald-Venturi household could be heard blocks away, and remained imbued in the minds of all who heard it, just as the vision of a dead child will forever imbue the parent's mind with the horrid memory.

After all, Dark Obsessions never end well.

_Of course._

Of course.


	4. Flashback: What Happened

This is the most graphic the story gets. While it is still pretty much all implied, the implications are really horrid. In fact, I was creeped out when this popped into my head out of nowhere.

* * *

The moment that the family had walked out the door, she felt something strange form in her stomach. If she trusted her gut feeling more, she would have recognized the emotion that screams, "GET OUT, NOW!" and is right a good deal of the time. However, priding herself in her rationality over her gut feeling, she ignored it.

Her mistake.

It took him no time to find her sitting in her room, doing something completely appropriate and responsible. She was frightened to look up to see him standing there in her doorway with that confounded look in his eyes. Except, this time, it was darker and more chill-inducing.

After her body produced the above-named reaction, she bravely, foolishly asked, "What do you want?"

And then all Hell was loosed in the calm, suburban home.

* * *

The first time he used her, it _hurt_. And it hurt much more than she expected. But if she had been given time—even a little—to recover, she believed she could have gotten over it rather well, considering the situation (_she would have, indeed_).

But he was not feeling very merciful, it seemed, today.

The next few times, she became desensitized to it, jaded and bitter. This just might have bided her time until the weekend was over, when she could get therapy and get over it, eventually. It would have been a good defense mechanism (_it would have worked!_), but for one thing.

He noticed it.

After that came the violence that battered her already soiled self to a breaking point from which she did not think she could recover (_but she might have, if she had just been given the chance!_). At this point, she was just wishing he would hit her too hard, just once, so she would pass out and would not have to _be_ there to experience it.

Apparently, he had no soft side left to even do that small thing for her.

* * *

He had finally fallen asleep (_at last!_). She was now taking a shower, trying to rid herself of the feeling of _him_ all over her body, trying to lessen the mental and physical scars and bruises all over herself. She had been in there so long that the hot water had run out and heated back up again. She had been keeping her mind occupied with escape plans to avoid thinking about what had actually happened; all the while salty tears streamed down her face and mingled with the dirty water. But she was so engrossed in her planning, her denial was working so well, that she did not hear him wake up. She did not hear him get up, open his door and close it, walk across the hall and into the bathroom.

She was so preoccupied with _not_ thinking about it, in fact, that she did not hear him until she _saw_ him pulling back the shower curtain.

* * *

The brink of disaster had officially been reached, surpassed, and left behind with a swirl of dust. This time, there were no words in her mind to describe the horrific things he was doing. (_It must have been bad if she was _speechless. _She always had something to say._) All of her emotions were ambivalent, and could not decide amongst themselves which would gain dominance over the others, and assert itself; she did not even have the liberty to say, "I feel so ___________. What can I do about it?"

She just wanted it all to end.

* * *

It did end. But unfortunately, not in the way she had hoped. For it ended not with his satiation, nor did it end with her escape.

It ended with a knife drawn across skin, precious blood spilling onto the floor. It ended with messy consequences. But what other kind of consequences are there when sin is involved? (_Surely you did not expect otherwise?_) There was no just punishment for crime, no words spoken meant to heal. There was only one of the two left alive, if you could even call what was left a living. This was like the ending of a _real_ fairy tale, like the ones where the Little Mermaid is turned to foam and the one where the Little Match Girl dies. There was no happy ending where the Knight in shining armor slays the Dragon and rescues the the fair Maiden.

No, today the Dragon has won. The Knight himself has been slain and the Dragon has devoured the Maid and had his fill.

(_What happens tomorrow?_)

* * *

Like all of the dark fairy tales used as scare tactics to keep young children in line, this, too, has a moral.

Make sure your Obsessions are fixed on the right Thing, or rather, the right Someone. Otherwise, humanity makes a ruddy mess of itself, does it not?

(_If you do keep your eyes fixed upon the Knight rather than the Dragon, then you slay the Dragon with the help of the Knight, free the Maid—who, you discover, is you yourself—and right the world once again. But you cannot do it alone._)


	5. Epilogue

The creature sat in the middle of the dark, filthy city with nowhere to go, no one to turn to, and nothing to keep it going. It was covered in grime, and a long way from its real, warm, and loving home. But do not misunderstand me. It is not to be pitied. It brought its fate upon itself by doing horrible, awful things that should never be done to anyone. When it left its (already pathetic and dying) morals behind, it forfeited the right to be pitied or shown mercy.

For it had only four real lines it had decided not to cross, that it would be wrong to cross.

Not crossing one out of the four was okay, right?

_Of course?_

Of course not.

But despite this forfeit of rights, this gross, flagrant and insulting disregard for lines not to be crossed, there stands Another with it, offering His hand with forgiveness and mercy. Of course, what it had done was wrong, and it realized this, but could not get help on its own. And with the help of a Hand that never let go, the creature, the it, was able to become human again, and a better self than before.

He had finally found the right Obsession. The Magnificent Obsession.

At last.

_Of course?_

Of course.

Magnificent Obsessions _always_ end well. They _heal_.

_Of course._

Of course.

* * *

I couldn't bear for this to end on such a depressing note. Even though it has a valid moral to it, I went about showing the moral the depressing way, and I thought it could use a little positive note to it, so the moral wasn't suffocated by the darkness in this story. I hope you enjoyed it (as much as you could anyway) and that it made you think.

I'll bet you can guess now which character dies and which one lives. But I meant it to remain ambiguous, so you can decide either way.

Thanks for coming along for the ride!


End file.
